Mount Sinabung spews ash as it is pictured from Sibintun village in Karo district, Indonesia's north Sumatra province November 18, 2013. Mount Sinabung continued to spew volcanic ash throwing a plume 8,000 meters into the atmosphere on Monday as thousands of residents remained in temporary shelters fearful of more eruptions, according to local media. REUTERS/Roni Bintang (INDONESIA - Tags: DISASTER ENVIRONMENT)

Two volcanoes erupted in Indonesia on Monday, with one forcing flights to be rerouted and stopping thousands of people who had already been evacuated from returning home.Mount Sinabung on western Sumatra island, which has been erupting on and off since mid-September, shot volcanic ash around 8,000 metres into the air.It also meant that more than 5,000 people who had recently been evacuated from the area around Sinabung due to its eruptions were unable to return home. On the main island of Java, Indonesia's most active volcano, Mount Merapi, spewed a column of ash and smoke some 2,000 metres in the morning.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: Refugees sleep inside a church set up as a temporary evacuation center on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: Sumarni Br.Sitepu packing her stuff as she prepares to leave her house in Mardinding village to a temporary evacuation center on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

Mount Merapi spews volcanic material as it erupts as seen from Pakem near the ancient city of Yogyakarta, Indonesia, early Monday, Nov. 18, 2013. Two volcanoes, Merapi and Mount Sinabung, erupted Monday, prompting warnings for flights and evacuation preparations, official said. (AP Photo/Slamet Riyadi)

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Villagers sit on a truck being evacuated from their village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Mount Sinabung spews pyroclastic smoke as seen from Tigapancur village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: A puppy is seen at an abandoned village in Mardinding village, located just less than three kilometers from mount Sinabung on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: A farmer show tomatoes covered in ash at his field after Mount Sinabung errupted spewing volcanic materials in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

A farmer wearing a face mask works on a field covered with volcanic ash from the eruption of Mount Sinabung in Kuta Mbaru, North Sumatra, Indonesia, Monday, Nov 18, 2013. Two volcanoes, Sinabung and Mount Merapi, erupted Monday in the country, prompting warnings for flights and evacuation preparations, official said. (AP Photo/Mafa Yuli Ramadani)

Villagers ride a motorcycle on a road covered with volcanic ash from the eruption of Mount Sinabung in Kuta Mbaru, North Sumatra, Indonesia, Monday Nov 18, 2013. Two volcanoes, Sinabung and Mount Merapi, erupted Monday in the country, prompting warnings for flights and evacuation preparations, official said. (AP Photo/Mafa Yuli Ramadani)

A woman looks on as Mount Sinabung spews ash, as pictured from Sibintun village in Karo district, Indonesia's north Sumatra province November 18, 2013. Mount Sinabung continued to spew volcanic ash throwing a plume 8,000 meters into the atmosphere on Monday as thousands of residents remained in temporary shelters fearful of more eruptions, according to local media. REUTERS/Roni Bintang (INDONESIA - Tags: DISASTER ENVIRONMENT TPX IMAGES OF THE DAY)

A woman carries a bucket full of ash-covered tomatoes on her head, at Mardingding village shortly after Mount Sinabung spewed volcanic ash in Karo district, Indonesia's north Sumatra province November 18, 2013. The volcano continued to emit volcanic ash on Monday, throwing an 8,000m (26,247 ft)-high plume into the atmosphere, as thousands of residents fearful of more eruptions remained in temporary shelters, according to local media. REUTERS/Roni Bintang (INDONESIA - Tags: DISASTER ENVIRONMENT FOOD AGRICULTURE)

MEDAN, SUMATRA, INDONESIA - NOVEMBER 15: A villager watching cold lava flow from mount Sinabung in Gamber village on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

A youth wearing a mask, stands behind a fence used as a trellis on which to grow tomato plants, at Mardingding village shortly after Mount Sinabung spewed volcanic ash in Karo district, Indonesia's north Sumatra province November 18, 2013. The volcano continued to emit volcanic ash on Monday, throwing an 8,000m (26,247 ft)-high plume into the atmosphere, as thousands of residents fearful of more eruptions remained in temporary shelters, according to local media. REUTERS/Roni Bintang (INDONESIA - Tags: DISASTER ENVIRONMENT AGRICULTURE)

A rescuer stands after Mount Merapi, background, erupted in Cangkringan, near the ancient city of Yogyakarta, Indonesia, early Monday, Nov. 18, 2013. Two volcanoes, Merapi and Mount Sinabung, erupted Monday, prompting warnings for flights and evacuation preparations, official said. (AP Photo/Slamet Riyadi)

Mount Merapi spews volcanic material as it erupts as seen from Pakem, near the ancient city of Yogyakarta, Indonesia, early Monday, Nov. 18, 2013. Two volcanoes, Merapi and Mount Sinabung, erupted Monday, prompting warnings for flights and evacuation preparations, official said. (AP Photo/Slamet Riyadi)

MEDAN, SUMATRA, INDONESIA - NOVEMBER 15: Villagers drive a motorcycle past mount Sinabung spewing ash in the background in Kuta Tonggal village on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: Sumarni Br.Sitepu carries her belongings as she leaves her house in Mardinding village to a temporary evacuation center on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SUMATRA, INDONESIA - NOVEMBER 15: A view of mount Sinabung spewing smoke is seen from Tiga Pancur village on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SUMATRA, INDONESIA - NOVEMBER 15: A woman walks as a painting of mount Sinabung erupting is seen on a truck in Suka Nalu village on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: A woman sits outside a church set up as a temporary evacuation center on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: Refugees sleep inside a church set up as a temporary evacuation center on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: Sumarni Br.Sitepu carries her belongings as she leaves her house in Mardinding village to a temporary evacuation center on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 15: Puppies are seen at an abandoned village in Mardinding village on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SUMATRA, INDONESIA - NOVEMBER 15: Chairs and sandals covered by ash are seen at an abandoned village in Mardinding village, located just less than three kilometers from mount Sinabung on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SUMATRA, INDONESIA - NOVEMBER 15: Villagers watching cold lava flow from mount Sinabung in Gamber village on November 15, 2013 in Karo district, South Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewinging ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: A man looks at Mount Sinabung spews pyroclastic smoke as seen from Berastagi village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Mount Sinabung spews pyroclastic smoke as seen from Berastagi village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: A farmer stands at his tomato field covered by ash after Mount Sinabung errupted spewing volcanic materials in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Villagers harvest potatoes at their field, located just less than four kilometers from mount Sinabung in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Mount Sinabung spews pyroclastic smoke as seen from Berastagi village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: An elderly woman is evacuated from the village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Refugees are seen at temporary evacuation centre following another eruption of Mount Sinabung in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Villagers carry their belongings as they await transport to a temporary evacuation center following another eruption of Mount Sinabung in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Mount Sinabung spews pyroclastic smoke as seen from Berastagi village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.

MEDAN, SOUTH SUMATRA, INDONESIA - NOVEMBER 14: Mount Sinabung spews pyroclastic smoke as seen from Tigapancur village in Karo district on November 14, 2013 in Medan, Sumatra, Indonesia. Up to 4,300 residents have been evacuated from five villages in North Sumatra due to the volcanic eruptions of Mount Sinabung. The volcano has been erupting for several days, spewing ash and lava 2.5 miles into the sky.